Photo-protective effect of beta-carotene- Gum Arabic microencapsules on the riboflavin-mediated photodegradation of milk

BOIERO MARIA LAURA; MANDRIOLI MARA; RODRIGUEZ-ESTRADA MARIA T.; BORSARELLI, CLAUDIO; GARCÍA, NORMAN A.; MONTENEGRO, MARIANA

CORDOBA

Encuentro; XI Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2012

Inter-American Photochemical Society

Riboflavin (Rf) or vitamin B2 is essential for several biological process, such as lipid metabolism and red blood cell formation, among others. In the daily diet, milk is the most important source of riboflavin. However, after opening the packaging, sunlight and/or artificial light exposition of milk induces a fast degradation of Rf and other components, thus reducing the nutritional quality of milk. These unwanted reactions are initiated by the excited triplet state of the flavin, i.e. 3Rf* which, in presence of molecular oxygen, is an effective generator of singlet molecular oxygen (O2(1Dg)), a reactive oxygen species able to oxidize Rf, vitamins A and D, lactoproteins, and lipids. An important goal of the food industry is to develop methods that reduce the detrimental effect of the combination of Rf + O2 + light, without a significant impact on safety and sensory properties of milk. A trivial photo-protection mechanism is to avoid light excitation by using protective packaging material. A second option is to physically quench either 3Rf* or O2(1Dg), by means of suitable quenchers. In this work, we explored the photo-protective capability of microcapsules composed by b-carotene and Gum Arabic (BCGA) and empty Gum Arabic microcapsules (GA) prepared by spray-dried, on the photooxidation of Rf in commercial milk samples stored under darkness and fluorescent light at 4°C. The photo-stability of Rf in milk samples with and without microcapsules, was analyzed by HPLC with diode array and fluorescence detection. The addition of 1.36 mg/mL GA and BCGA microcapsules decreased the rate of Rf photodegradation by approximately 11% and 30%, respectively. The global photoprotection effect is explained in terms of inner-filter effect of the microcapsules, and quenching of both O2(1Dg), and 3Rf* by microcapsules. The results indicated that Rf photodegradation in milk can be strongly reduced by the addition of small amounts of BCGA microcapsules.